F04D29/128—Shaft sealings using sealing-rings especially adapted for liquid pumps with special means for adducting cooling or sealing fluid

F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING

F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL

F16J—PISTONS; CYLINDERS; SEALINGS

F16J15/00—Sealings

F16J15/16—Sealings between relatively-moving surfaces

F16J15/34—Sealings between relatively-moving surfaces with slip-ring pressed against a more or less radial face on one member

F16J15/38—Sealings between relatively-moving surfaces with slip-ring pressed against a more or less radial face on one member sealed by a packing

Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS

This invention relates to shaft seals and more particularly to seals for pump shafts.

Among the several objects of the invention may be noted the provision of an improved shaft seal readily applicable to existing pumps as well as to new pumps or the like; the provision of an improved shaft seal in which sealing pressure is derived from a source of fluid under pressure,such as compressed air; the provision of a shaft seal which, while having a minimum of parts subject to wear, provides a tight seal against leakage and in which wear is taken up by the pressure of the seal-actuating fluid; and the provision of a shaft seal of the class described which is easy to install and which is reliable in operation and has a relatively long useful life. Other objects will be in part apparent and in part pointed out hereinafter.

The invention accordingly comprises the elements and combinations of elements, features of construction, and arrangements of parts which will be exemplified in the structures hereinafter described, and the scope of which will be indicated in the following claims.

In the accompanying drawing, in which one of various possible embodiments of the invention is illustrated,

Fig. 1 is a longitudinal section of a shaft seal of this invention; and,

Fig. 2iis' transverse section taken on line 22 of Fig. 1.

Corresponding reference characters indicate corresponding parts throughout the several views of the drawing.

Referring to the drawing, there is shown at l a portion of a pump casing having a hollow open-ended cylindrical shaft housing 3. The pump shaft extends through this housing. Threaded on the inner end of the pump shaft is the pump impeller I. These pump elements are generally conventional, and no further description is believed necessary except to state that the internal diameter of the housing 3 is larger than the diameter of the shaft 5 so that there is considerable annular space constituting a chamber 9 around the shaft within the housing which receives the elements of the shaft seal of our invention.

Included among the elements of our new shaft seal is a hard seal ring H which is fixed to and hence rotates with the shaft at the inner end of the chamber 9. As herein illustrated, the ring U is fixed to the shaft by being mounted on a reduced-diameter portion l3 of the shaft adjacent its inner threaded end I! and is compressed between the shaft shoulder I! at the 3 Claims. (01. 286.-9)

. 2 root of portion I3 and the impeller I threaded on l5. Other suitable ways of fixing the-ring on the shaft will readily suggest themselves. We prefer to make the ring l I of stainless steel with a hard outer wearing face 19, such as Stellite, and it will b understood that the ring may b made of other suitable materials.

Further included among the elements of our new seal is a head2l for closing the outer end of the cylindrical housing 3 having an integral sleeve 23v extending into the housing receiving the pump shaft 5. The head is fixed to the housing by screws 25 threaded into tapped holes 21 in the outer end of the housing. The head preferably has a precision fit with the end of the housing to avoid any necessity for use of a gasket between the head and the end of the housing, but such a precision fit may be dispensed with and a gasket used to provide a sealed connection as between the. head and housing. The internal diameter of the sleeve is greater than th diameter of the pump shaft so that there is a substantial clearance between these parts (for example, a e? clearance on the radius). The length of the sleeve is such that its inner end is closely adjacent but not in contact with the ring II (for example, being spaced 1%" from the ring H).

We prefer to mak the head 2| and its integral sleeve 23 of stainless steel and it will be understood that any other suitable material may be used. The head 2| is provided with an inlet port 29 for admitting fluid under pressure (compressed air, for example) to the chamber}. I

The sleeve 23 at its inner end has a pair of diametrically opposite axial keyways 3| formed by axially slotting the sleeve. Axially slidable on the sleeve is a sealing ring 33 having its inner face 34 in running sealing engagement, as will be later made clear, with the outer wearing face IQ of the ring ll on the shaft. The ringv 331s held against rotation, while being axially slidable on the sleeve, by having integral keys 35 slidable in the keyways 3|. We prefer to make the ring 33 a carbon ring. The internal diameter of the ring 33 is greater than the external diameter of the sleeve 23 so that there is a substantial clearance between theseparts (for example,

clearance on the radius). The periphery of the ring is made frusto-conical, as indicated at 36, convergent outward.

Backing the carbon ring 33 is a packing ring 31 which is made of a solid deformable material preferably having, even when dry, a low c'oeflicientof friction. The packing ring 31, as illustrated, is generaly of cup-shape,-having a base or main body portion 39 provided with a sleevereceiving central opening 4| and an annular skirt or lip 43 extending inward from the base and surrounding the carbon ring 33. The internal surface of the extending skirt or lip 43 is made frusto-conical as indicated at corresponding to the frusto-conical periphery 36 of the carbon ring. The skirt or lip 43 is longer in axial direction than the thickness of the carbon ring. The outer surface of the skirt 43 is coextensive with the outer periphery of the main body portion 39 of the packing ring 31. In the cylindrical exterior of the packing ring at the .root of the wall or lip 43 is an annular groove 46.

and radial relief ports i'llprovidefor'communi- ,low coenicient of friction inrespect tormetal even when :dry, Lit is substantially chemically inert. However, other suitable materials may beused.

iBacking the packing ring .is -,a follower ring lii -axially slidable on the sleeve '23. The follower rringhas an. annular nose 51 of wedge-shape in cross-section corresponding to and entered in the-groove .49 in; the base of the packing ring. Thefollower ring maybe made of metal, such as-stcel orbrass, or itmay be made or .any other :suit'ablematerial, for. example a chemically inert plastic material if necessary. or desirable.

The operation of the r seal as follows:

Upon introduction of. any fluid under pressure --into the pressurechamber 9 through the inlet -port*29 in the-head 2|,thefo1lower ring 55, the packing ring 3l and the carbon ring'33 .are driven "to the left as viewed in Fig; 1 to effect. pressureseal-ing engagement as between the innerface 13 i =-of the carbon'ring and'the outer wearingface 90f the rotary ring I i on the shaft 5. iThiS-Sfiill is a-rotary running seal. "The" follower ring acts as-a-piston, its outer or right face being subjected to the fluid pressure. "The pressure "fluid will ordinarily be compressed air, butany other suitable pressure fluid, gas or liquid,- may be utilized. For example, pressure may 'be'developed inchamber 9 behind the'follower-ring55 by connecting a container of compressed carbon dioxide ggas-tof the inlet-port 2s.

Thus, seals are obtained between wthe non- :rctaryicarbon ring '33 and: the: rotary ring 'I I bettween the packing; ring t'i and housing'firat lips 43 and-53, and between thepacking ringand ,sleeve at: lip 5|. The firstof thesegisarunning eradial seal,.-the latter two are-axial seals of con- 4 siderable axial extent along the internal surface of the housing 3 and the external surface of the sleeve 23. The pressure fluid in chamber 9 (for example, air) is effectively excluded from the pump by reason of the provision of relief ports 41. Should any air leak past the seal at lip 53, it will be vented to atmosphere via groove 56, ports 41, the clearance space between the carbon ring and -the.,sleeve, andithe clearance space between the sleeve'and the pump shaft. This is often important to avoid introduction of the seal-maintaining pressure into the pump system since this pressure may be higher than desired in the pump system. Also, in the case of air, for example,

' introduction of :air into some pumps may cause them to become-air-bound.

Upon wearing of the carbon ring 33, the wear is automatically taken up by the action of the pressure-in the chamber 9 behind the follower ring 55 forcing the follower ring, packing ring 31 and :carbonringfiii:toward the rotary'ring H. :Here

it is to be noted that with the packingringmade of Teflon, -;which has a low coefficient of; friction with respect to metal even when dry, the packing ring. can slide axially without breakingits sealing :engagement with the internal surface of housing -3 and the external surface of sleeve 23.

' In some cases where the pump isused for pumping liquid which does not result in formationof scale, the forward H1343 ofthepacking ringjii'l may Joe-eliminated.

It willbe iunderstoodthat'it is contemplated that the parts'H-ZE, 33, 3? and 55 maybe-sold -as a -unit for installation by. the purchaseron-a pump.

In view of the above, it will be seen that the several objects of the invention are achieved and other advantageous results attained.

As various changes could be made in the above constructions without departingfrom thescope of the invention, itis intended that all matter contained in the abovedescription or shown in the accompanying drawing shall be interpreted as illustrative and not in a limiting sense.

':'We claim: '1.A- seal for-ashaft-which extends outof a casing through a cylindrical opening f-iarger diameter than'the shaft,-comprisin 'g-'a head on .the casing closing the outer end of theopening and receiving'the shaft, a sleeve extending from the head into the opening, the shaft being rotary .inthe sleeve, theexternal diameter of thesleeve 'being'less than the 'diameterof, the op.en ir1 g. to provide an annularpspace around the-sleeve, a sealingringirotarygwiththe shaft adiacentfthe inner end.,.of. .the sleeve a packing ringislidable on the sleeve in said annular space said packing ring being formed .of solid, deformable. material capable of sliding ,on the internal cylindrical surfaceof the casing in the openingand on theexternal surface of the sleeve, the packing ring ,having ,a,;-main :body .portion wherein there, is -a sleeve-receiving central :opening with an annular gskirt, proi ecting inward; fromthe main, body; portioni in-the5 direction;toward-.the vrotary= sealing ring; the outer surface-10f. theskirt" being coextensive with the outer periphery ofthe-main body portion; a non-rotary sealing ring located inthe skirt and slidable on the sleeve,-'the skirt and the nonrmtarysealing ring having'mutually engaging wedge, surfaces for, effecting radial expansion .of .the skirt .into ,sealing engagement with the, surface of thecasing inthe openin tthe packing ring; also having inner and ,outenannular lips projecting outward from its main body portion and adapted to be spread apart for sealing engagement of the outer lip with the surface of the casing in the opening and of the inner lip with the sleeve, a port being provided for introducing fluid under pressure into the annular space around the sleeve behind the packing ring for pressurewise forcing the packing ring and the non-rotary ring toward the rotary sealing ring and for effecting radial expansion of the skirt and spreading of the annular lips.

2. A seal as set forth in claim 1 wherein the packing ring is formed to hold the non-rotary ring spaced from the main body portion of the packing ring, and wherein the packing ring has at least one radial vent port from the space between the non-rotary ring and the main body portion of the packing ring to the outer periphery of the packing ring.

3. A seal as set forth in claim 1 further com- 6 prising a follower ring slidable on the sleeve backing the packing ring having means for entry between the lips to spread them apart.